Web Developer

The Web Developer extension adds a toolbar button to the browser with various web developer tools. This is the official port of the Web Developer extension for Firefox.
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The best place for support is not in the reviews section below, but on the Web Developer site in the help:
http://chrispederick.com/work/web-developer/help/
Also available there are a full set of release notes:
http://chrispederick.com/work/web-developer/history/chrome/